Unreal Torpedo Spotting

[RedParadize]

I think that a great deal can be explained trough the context in which sonar was used. Do not forget that they were human operated, single direction device and subject to the environment in which they were operated. It isn't surprising that both terrible and great performance were recorded.

[DougToss]

16 hours ago, madham82 said:

My bad, my sarcasm was lost. Wasn't arguing about it existing in game, was just being sarcastic that it was in the game to start with. In general hit rates are much higher than IRL already, so no surprise there are issues with balance. 

I know this discussion is about Torpedos, but @Nick Thomadis - the higher hit rate is what is causing issues for every step of the line down! Ships have to be armoured and gunned entirely differently than they would be in reality because engagements are so different!

 

I digress, but you can very easily test this by using approximately the same ship in UA:D, Jutland Pro and RTW 2. During the battlecruiser exchange at Jutland the British scored 11 hits iirc. They would easily get 100+ in the same conditions in UA:D right now. That means any sensible person would have to put 16 inch guns and vastly more armour on the German battlecruisers. 
 

To return to the problem at hand, is it possible that in this instance sonar acted more like a primitive RWR, or IRWR - only indicating that there was a launch, but not range or bearing? From what I know of German sonar arrays, that seems more feasible than  plotting the torpedo. It would also still be useful in game and prime players to look for visible tracks.

 

I was reading about Tactics in 1912, I’ll look for the passage later, and it said that evasive drills were taken if torpedos were suspected to have been launched. Of course at the ranges torpedos could reach by 1910, you couldn’t see the shot leave the tube, and I think trails were weak until more advanced torpedos came along, but the idea was to turn towards the bearing of the launch, so that you would pass through the “rake”.

 

It could be as easy as telling players “if you think a torpedo has been launched, turn directly towards or away from it”, having sonar alert players to launch would just help them know to take evasive action, not tell them exactly when and how to evade by accurately plotting the torpedo in the water.

 

 

 

Edited October 2, 2021 by DougToss

[theCarthaginian]

4 hours ago, DougToss said:

I know this discussion is about Torpedos, but @Nick Thomadis - the higher hit rate is what is causing issues for every step of the line down! Ships have to be armoured and gunned entirely differently than they would be in reality because engagements are so different!

I digress, but you can very easily test this by using approximately the same ship in UA:D, Jutland Pro and RTW 2. During the battlecruiser exchange at Jutland the British scored 11 hits iirc. They would easily get 100+ in the same conditions in UA:D right now. That means any sensible person would have to put 16 inch guns and vastly more armour on the German battlecruisers.

To return to the problem at hand, is it possible that in this instance sonar acted more like a primitive RWR, or IRWR - only indicating that there was a launch, but not range or bearing? From what I know of German sonar arrays, that seems more feasible than  plotting the torpedo. It would also still be useful in game and prime players to look for visible tracks.

I was reading about Tactics in 1912, I’ll look for the passage later, and it said that evasive drills were taken if torpedos were suspected to have been launched. Of course at the ranges torpedos could reach by 1910, you couldn’t see the shot leave the tube, and I think trails were weak until more advanced torpedos came along, but the idea was to turn towards the bearing of the launch, so that you would pass through the “rake”.

It could be as easy as telling players “if you think a torpedo has been launched, turn directly towards or away from it”, having sonar alert players to launch would just help them know to take evasive action, not tell them exactly when and how to evade by accurately plotting the torpedo in the water.

We can understand why the Devs 'compressed' things a bit as far as hits - very few players want to spend hours in a game with 50 ships plowing around the ocean, fight a 24 hour (realtime) long battle in half-a-dozen 2 hour long main phases and a dozen short-duration skirmishes... and sink maybe 7 or 8 ships (and few of them be large ones). It, sadly, goes back to the 'Realism vs Entertainment' issue - and that people could by and large want to see more substantial results for their efforts.

As far as the torpedoes:
Yeah, the launch sequence for a torpedo is the dead giveaway... a ship GENERALLY makes a highly-recognizable, easily detectable, and simple-to-counter (at anything other than stupidly close ranges) set of course changes when firing a torpedo. They have to close to a specific range bracket, turn to within a certain angle of approach, hold that course for a predictable period of time, and then (presumably, if they are acting rationally) change course again to escape the wrath of their enemies. Anyone looking for a torpedo attack would notice a ship that was engaging in this pattern, and would act accordingly. Of course, that DOES assume that the opponents can ACTUALLY SEE YOU - say, they aren't making smoke while you are making smoke (like in my original post) - and know that you are doing this.

Given favorable acoustic conditions, a warning 'cone' like the RDF 'finger' pointing out a suspicious contact (in, say, red - to differentiate) in a given arc would be appropriate. The debate is over the timeframe of the warning: exactly how far out would you be able to detect that the threat is actually a specific threat rather than something they thought they heard. That's where the 'vigorous discussion' part comes in; what would the sonar tell them, how fast they are going to be able to interpret that, and how it would integrate with the other information you get from other sensors to give a whole picture.

[DougToss]

34 minutes ago, theCarthaginian said:

Given favorable acoustic conditions, a warning 'cone' like the RDF 'finger' pointing out a suspicious contact (in, say, red - to differentiate) in a given arc would be appropriate. The debate is over the timeframe of the warning: exactly how far out would you be able to detect that the threat is actually a specific threat rather than something they thought they heard. That's where the 'vigorous discussion' part comes in; what would the sonar tell them, how fast they are going to be able to interpret that, and how it would integrate with the other information you get from other sensors to give a whole picture.

Given the German’s handling of radar… lol I wouldn’t place a lot of confidence in that. Information management as a whole in German surface ships seems to have been subpar. Even during the Channel Dash, which was doubtlessly operationally successful, on the tactical level I’m not convinced anyone on the bridge of a given Kriegsmarine ship knew what was going on. 

[theCarthaginian]

59 minutes ago, DougToss said:

Given the German’s handling of radar… lol I wouldn’t place a lot of confidence in that. Information management as a whole in German surface ships seems to have been subpar. Even during the Channel Dash, which was doubtlessly operationally successful, on the tactical level I’m not convinced anyone on the bridge of a given Kriegsmarine ship knew what was going on. 

Nor do I... not while it was happening - in fact, I'm quite skeptical that the sonar crew figured out what they heard was a torpedo. I'm of the opinion that the 'information integration' we see in the log happened on the bridge, and that the recording of 'torpedo detection' was the result of sonar relaying a "probable intermittent contact" report, lookouts reporting suspicious enemy asset behavior, and then the actual spotting of a wake or group of wakes. Then you have that eureka moment, and realize what the sonarman heard in that direction for the last 5 minutes (probably defined as "out there, that-a-way" for most of it) was the torpedoes fading in and out of detectability as conditions changed. Subs actually have a bit of an advantage here, as a crew of 70 - 100 men is a LOT easier to disseminate information amongst than a cruiser with a crew nearing a fifteen hundred. In one situation, you simply call someone's name/title out and he takes a few steps or even just turns his head... in another, you're dealing with a chain of a dozen or so guys that are spread over what could generously be called "Hell's half acre", and none of whom can actually see or hear what the other guy is doing or looking at - and will, in battle, be contending with another dozen or so groups just like that vying for the attentions of the one person that's supposed to be coming up with all the answers.

I've never felt that the information management of any navy in WWII was particularly bad, in that it roughly corresponded to what had been considered acceptable for centuries. What I have felt is amaxement that some navies and, more specifically, particular fleets within some navies evolved the astounding levels of information management that they accomplished. The Germans were at a terrible disadvantage in that regard, not really conducting any large scale fleet actions like some fleets... like, say, the Italians. 😉 German availability meant that they never had more than a handful of large ships out of the relatively few that they possessed in coordinated action at once, and that's how you get good at information management on large ships.

[arkhangelsk]

14 hours ago, DougToss said:

To return to the problem at hand, is it possible that in this instance sonar acted more like a primitive RWR, or IRWR - only indicating that there was a launch, but not range or bearing? From what I know of German sonar arrays, that seems more feasible than  plotting the torpedo. It would also still be useful in game and prime players to look for visible tracks.

I don't know what is this resistance to the idea of it being possible to have a somewhat competent hydrophone system.

Quote

 

Admiral Lütjens’s staff had been carefully plotting the British ships’ maneuvers with their hydrophone system. Suffolk would lose radar contact on the outer leg of her port maneuver for approximately ten minutes. Swinging back to starboard, radar contact would be reestablished. Bismarck had been zigzagging as well. Nudging Bismarck a little more to starboard each time to see how the British ships would react, the German admiral finally decided at 0306 to make his move. A check with the hydrophone system indicated that there were no signs of ship movement to starboard.

Garzke, William H.; Dulin, Robert O.; Jurens, William; Cameron, James. Battleship Bismarck: A Design and Operational History (p. 309). Pen & Sword Books. Kindle Edition. 

 

You can eventually derive range, course and speed using only bearings, but if you don't even have somewhat decent bearings, you aren't plotting.

Never mind:

Quote

 

1745hrs: Hydrophone report: Bearing 330° torpedo. Hard to port. Ship turned 30° to port.

Koop, Gerhard. Battleships of the Scharnhorst Class: Warships of the Kriegsmarine . Pen & Sword Books. Kindle Edition. 

 

Quote

 

1823hrs: Hydrophone report: Torpedo bearing 10°, course plotted. 1824hrs: Hydrophone report: Torpedo passed ahead.

Koop, Gerhard. Battleships of the Scharnhorst Class: Warships of the Kriegsmarine . Pen & Sword Books. Kindle Edition. 

 

 

[DougToss]

It’s more that, @theCarthaginian put beautifully, I wonder about theoretical capabilities versus actual utility. Though those reports are in line with the RWR/IRWR comparison I was musing about. 

[theCarthaginian]

51 minutes ago, arkhangelsk said:

I don't know what is this resistance to the idea of it being possible to have a somewhat competent hydrophone system.

You can eventually derive range, course and speed using only bearings, but if you don't even have somewhat decent bearings, you aren't plotting.

Never mind:

 

It's not a resistance to a 'competent hydrophone system' - it's a resistance to some people confusing 'theoretical maximums' with 'consistent performance under combat capabilities.' Those two things are a fair piece away from each other, realistically... yet armchair quarterbacking on third-hand sources sometimes leads to their confusion.
For instance, the 'maximum effective range' on my beloved M249 was (theoretically) 1000m for an area target.
Even in Iraq, that was a most generous assumption:
- It first assumes that I'm engaging on open terrain that lets me have that kind of option, and I was in town rather often without that kind of LOS.
- It doesn't take into consideration weather on any given day... if there was a sandstorm, every weapon had a MER of "the end of my nose."
- Even the sunlight could play hell with that 1000m figure - if it was a particularly blistering day, the haze and glare could make you lose economy cars at a kilometer.
- Iraq wasn't all flat scrublands or gentle dunes... and it's hard to get 1000m worth of LOS in a wadi.

Likewise, the performance that is exhibited in one engagement isn't indicative of the average performance of a sonar system.
Yet, it is seized upon by some as a mean performance... because it's the only well-known documentation.
That's called 'the mediocrity principle' - an assumption that all other things being equal, you got your single result because it was the most likely outcome. While that is a recognized principle, it is not something that you should engage in capriciously or regularly. And we have other information on the basic hydrophone design from multiple German sources, because it was used on U-boats. Reading the accounts of the boats gives us everything between 'we head it before we saw it' and 'we could have drove into a ship before hearing it' (largely attributable to weather near the surface).

So, I don't doubt the man heard something.
I don't doubt that he said it was possibly a torpedo when he got a good listen to it.
I DO DOUBT that he was tracking the torpedo from the instant of launch up to whenever he consciously decided to stop, constantly and consistently, and that no other information was used to verify what he saw or assist in identification of the torpedoes. THAT is just, bluntly, a dumb line of reasoning. When a sonarman reports a contact, it is SOP for it to be verified by multiple other methods - as many as possible under the circumstances. Lookouts WILL be told to check that bearing line. If it is likely a ship, it WILL be verified by RADAR if they aren't trying to avoid detection. Likewise, a radar contact would be verified by visual and sonar as soon as possible, if possible.
That's just how it works.
And what gets written in the ship's logbook is the sum of ALL those things.

 

[DougToss]

@theCarthaginian always happy to see another vet! I was on M777’s. I could write volumes on how 6 in guns perform in game. I also had to hump around a C9 from time to time, and feel your pain lol.

This is something I think a lot of veterans and military academics and professionals run into both in wargaming and pop history. Stats on hardware are easily available, and feels like empirical knowledge. It’s so hard to explain the soft factors, doctrine and other differences between theory and practice. This is particularly an issue with AFVs and Warships because I think oftentimes people think it is as simple as placing two tables side by side and comparing statistics.

There are a million reasons this is misguided, but as a Canadian my favourite is that as the poor bastards that had to take on the Big Cats in Normandy from day one, including in the hands of 12th SS, the humble Sherman had a favourable exchange ratio, even though you will still hear people say the Allies had to literally send 5 Shermans out to take one Panther or Tiger. It turns out there is more to it than armour thickness and gun calibre! 
 

For warships, I think Bismarck and Yamato loom large in the imagination, despite not accomplishing anything towards the outcome of the war, and with the exception of the Channel Dash, not really being that impressive in action. 
 

To your point, working in all areas, including Recce, STA and Artillery Command Post, you’re correct on how logs do not always reflect the full picture. I’ll give you an example:

Say the counterbattery radar picks something up. That will be processed as one report.

Whoever that battery is firing on will also enter a Enemy Shelling Report (shellrep) with location of enemy threat / impact, assessed line to gun line in mils, time between impact and firing.

At the same time, anyone who observed flash is sending up their reports, similarly anyone who heard the sounds.

We don’t know any of this on the Artillery Net, but our Surveillance and Target Acquisition guys are trying to verify the radar report. 
 

Our attached and other EW guys are at work because in 2021 an arty bty is never just the gunline, so they’re looking for the chatter, trying to plot the arty net, observer’s net, looking for their CB radars, doppler and weather radars, other DF stuff.  

 

At the same time, our FOOs and OPs are getting run up.

Possibly we are operating with battery RPV/Balloon, and are looking with that too. Possibly there is Bde/ISAF/US UAV or other imaging being consulted. We don’t see any of this.l

 

Brigade/Battlegroup has now processed some of the information from the people on other nets and is passing it down to our CP. Our CP is handing up our own reports. There are even more pieces left out here as all of this information is collated at the Staff,  run through Bde’s situation map, checked against the Int shop and Bde Arty O, etc. 
 

At the end of the day, when all of that is logged in the War Diary, it will read “Battery detected and engaged 1 Arty Bty, at (Grid, mil bearing, range)”, detected by CB Radar, log the time of the initial radar contact!

You can see that 1) The Radar Operator was aware of only a teeny tiny part of that,2)  the big picture was much longer, more laborious and used other methods,  3) The log alone only shows a sliver and superimposes the later, more complete picture onto the initial contact. Everything that came later explains what it was in hindsight, but it was not apparent, or at least not collated initially.  

Edited October 3, 2021 by DougToss

[arkhangelsk]

On 10/3/2021 at 11:53 AM, theCarthaginian said:

It's not a resistance to a 'competent hydrophone system' - it's a resistance to some people confusing 'theoretical maximums' with 'consistent performance under combat capabilities.'

First, we are already using combat logs, so at least we are not dealing with "theoretical" or even "highly optimistic and unrealistic test" results. In fact, we are dealing with pretty unfavorable conditions - the seas far from being a flat and the ships themselves moving at over 20 knots. And between Bismarck, Schanhorst and Prinz Eugen, we are at least not talking about one source.

Re German U-boats, the first thoughts that come to mind are as follows. Other than them just not listening in the right direction at the right time, there is a huge gap in operator quality. There are about 1000 U-boats versus ten battleships + heavy cruisers. Do you really think the average U-boat sonarman would be of the same cut? Third is the target - with the U-boats mostly trying to hear merchies and tiny escorts that are moving at low speeds (low noise).

Third, I don't want to deny the possibility of assistance that did not make it into the log, but there's still a huge gap between this and what DougToss is doing.

Quote

At the end of the day, when all of that is logged in the War Diary, it will read “Battery detected and engaged 1 Arty Bty, at (Grid, mil bearing, range)”, detected by CB Radar, [time of the initial radar contact]!

Sure, but in his scenario the CB radar still got the first contact and it would have provided at least an approximate position that is verified and possibly refined by any other available assets, especially UAVs many of which have straw-like vision. If no assets are available or they can't acquire / refute, and the need to suppress the battery exceeds that of the concern for collateral damage, fire can be opened on the coordinates from the CB.

What I understand Doug would do, based on his previous statement, is to insist (with no proof at all) that the CB radar was only a (nondirectional) "RWR" that did not even get an approximate bearing on the incoming shells, and it was other assets whose presence is never noted in the log that provided the firing data, leaving one to wonder whether the CB radar should be cited at all.

[DougToss]

An initial contact is kind of like a RWR, because CB and its operators wouldn’t be focussed in yet. It’s why shoot and scoot works, for mortars and rockets especially, we’re not going to plot them enough for unobserved CB fires until we have a better idea of where they are, which takes time, assets, and for them to fire again once we’re “looking”.
 

CB radar then, is kind of like a “(Possible) shell in the air” warning system, just like a RWR. We can see that there (might) be one, sort of guess where it came from and start all the wheels in motion. Like, @theCarthaginian said about sonar detecting that there (might) be a torpedo in the water. It’s a good comparison, for sure. 
 

I don’t disagree that if you were on the right bearing and primed to be on the lookout with a CB you can identify the signature of a battery firing. If they keep firing while you’re looking at them, you can count the number of guns and even guess at their calibre and angle of fire from time of flight, given enough time under the microscope. If they’re careless enough to keep at it, you can even make an educated guess at towed or SP based on their maximum rate of fire (if they sustain a high rate). No doubt, it’s sophisticated hardware and the theoretical capabilities are there. 
 

But, sometimes all you get it “there might be someone out there”. The reason the log would state that initial contact is that it got the ball rolling and everybody on the lookout. Or the Radar Troop hogs all the glory, matter of opinion lol.

[theCarthaginian]

8 hours ago, arkhangelsk said:

First, we are already using combat logs, so at least we are not dealing with "theoretical" or even "highly optimistic and unrealistic test" results. In fact, we are dealing with pretty unfavorable conditions - the seas far from being a flat and the ships themselves moving at over 20 knots. And between Bismarck, Schanhorst and Prinz Eugen, we are at least not talking about one source.

Re German U-boats, the first thoughts that come to mind are as follows. Other than them just not listening in the right direction at the right time, there is a huge gap in operator quality. There are about 1000 U-boats versus ten battleships + heavy cruisers. Do you really think the average U-boat sonarman would be of the same cut? Third is the target - with the U-boats mostly trying to hear merchies and tiny escorts that are moving at low speeds (low noise).

Third, I don't want to deny the possibility of assistance that did not make it into the log, but there's still a huge gap between this and what DougToss is doing.

1.) You are kidding, right?
The creme de la creme of sonar operators in the Kreigsmarine were put on a heavy cruiser? 🤣 I'm sorry, no... that's a MASSIVELY counterintuitive comment with neither grounding in rationality nor the ability to cite proof. Occam's Razor would lead one ot believe that the better sonarmen were on U-boats, simply by virtue of their ships' entire existence depending on how well that system is operated. Pulling a guy that can hear, differentiate, and triangulate targets at 40km from a sub to a surface ship is like taking the best door gunners in the Ia Drang valley out of their Hueys and making them Apollo Program Door Gunners. You lose any real utility that cannot be gained by other systems. We know this, because, no major Kreigsarine vessel was lost to surface-launched torpedoes in spite of several facing them. AGAIN, you are citing a single instance and applying the Mediocrity Principle in the face of convincing evidence across multiple nations that other circumstances point to this being an outlying case. Your argument is not based on logic, or it is rather based on bad logic.
2.) Again, you're making a false assumption. Lower frequencies carry farther in water than higher ones. This means that higher-frequencies - like what a torpedo gives off as opposed to, say, a churning Liberty ship propeller - attenuate FASTER and you won't hear them as far away. :-) Also, the Expansion engines that most merchant ships of the inter-war and WWII period used were orders of magnitude louder than a turbine-driven warship due to the fact that they caused far more vibration and impact forces that propagated through the structure and into the water. Turbines simply spin... the multiple expansion engines of a merchant ship and some escorts ware just like a car engine - a piston on a connecting rod that turned a crankshaft. If you own a car, fire it up and open the hood. Watch your engine sit and vibrate. Ever wonder why it isn't precisely hard-mounted to the frame, but instead has dampening mounts?
*ding, ding, ding*
We have a winner. :-D
So, your entire basis for the second part of your argument is utterly and irredeemably flawed.

[theCarthaginian]

PS - I find no records of Bismark or Scharnhorst having any sonar systems installed.
Could you point me toward your source for that?
If they did not, in fact, have them... well, you ARE dealing with a single instance - especially if those ships didn't exhibit exactly the same performance.

[DougToss]

Just generally speaking, the U-Boat arm got the pick of the Kriegsmarine. By the time the major surface units were expected to do no more than be bombed at anchor, I’m not sure why they would prioritize sending the top of the sonarman class there. I’m sure I can poke around for something on how the Kriegsmarine was kitted out for ASW and how their acoustics were.

From O’Hara’s On Seas Contested: The Seven Great Navies of the Second World War:

Antisubmarine Doctrine

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The minor role played by antisubmarine forces during World War I, when German surface ships sank only two submarines (by gunfire), failed to establish an antisubmarine warfare tradition in the German navy. Given the restrictions of the Versailles Treaty, the ban of U-boats, and the concentration on surface warfare, antisubmarine warfare was considered unimportant in the postwar period and was possibly influenced by British propaganda claims for the great efficiency of the Asdic underwater detection system introduced during the 1920s. Moreover, specialization in antisubmarine warfare was unlikely to advance an officer’s career.

During the Kriegsmarine’s peacetime expansion, the requirements of fleet operations occupied the small number of destroyers and torpedo boats, and they were ill equipped for the antisubmarine role. No purpose-built antisubmarine vessels were commissioned before the war. For the 1938 naval training exercise, a temporary Unterseeboots-Jagd (UJ, subchaser) flotilla was formed at Flensburg by modifying fishing vessels. Based on the experiences gained in the exercise, two UJ-flotillas were temporarily established in July–August 1939. Each flotilla consisted of eight modern fishing vessels, each displacing about a thousand tons. The intended return to their private owners was cancelled when war broke out one month later and the Kriegsmarine entered the war with sixteen auxiliary subchasers in commission.

Once war commenced, Germany’s sea-lanes were largely restricted to coastal waters along controlled territory with overseas trade quickly blocked by Allied navies. Standing combat instructions designated Germany’s few capital ships for independent raider operations in distant waters without close anti- submarine escort. Thus, German antisubmarine efforts were initially reduced to escorting warships and coastal convoys close to bases and along the coastline. Contingency plans in the event of war foresaw the conversion of civilian fishing trawlers and whalers into military ships for the antisubmarine role. However, many of these small, slow vessels carried inadequate antisubmarine equipment to prevent attacks. To compensate for the lack of ships and trained personnel, the Kriegsmarine deployed extensive mine barrages along the coastal shipping lanes. Moreover, apart from the mines, shallow water often kept enemy submarines out of these areas.

To meet the demand for personnel, an antisubmarine school, the UAS (U-Boot-Abwehr-Schule), was established at Neustadt on 25 September 1939. In November 1939 it moved to Gotenhafen and finally in July 1943 to Bergen, Norway, with a detachment at Hatvik, Norway. Using captured foreign submarines as target vessels, surface combat units were trained in antisubmarine techniques as far as operational needs allowed.

The lack of adequate ASW vessels, trained personnel, and offensive combat tactics was reflected by the small number of submarine sinkings by naval and air force units in all theaters of combat. Out of the ninety-four Allied submarines lost, surface ships sank only twenty-five (see table 2.1). Designated antisubmarine vessels accounted for 80 percent of these with the rest coming from torpedo boats, minesweepers, and other small units. In the absence of a naval air force command, the Luftwaffe never committed to ASW. Consequently, aircraft were not a serious threat to Allied submarines. Defensive mine barrages proved to be a most effective submarine-killer, espe- cially in the Baltic, the Black Sea, and along the Norwegian coast. However, apart from the Mediterranean, where the operational situation favored the use of submarines, German shipping losses to submarine attack remained small throughout the war. Allied submarine operations never impaired the vital transport of iron ore from Scandinavian ports or the supply of the German garrison in Norway and the Arctic theater.

 

ASW Equipment

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A great deal of work in the field of underwater acoustics was preformed using passive sets. One such set was called GHG (Gruppenhorchgerät) and consisted of two rows (one per each side) of Rochelle salt receivers in the forward part of a ship. The bearing of an incoming sound wave was detected by the processing of the signal delays in a compensator. All U-boats and most surface war- ships were equipped with GHG. An advanced version was fitted in the heavy cruiser Prinz Eugen. This set consisted of two rows with sixty Rochelle salt hydrophones at each side, arranged in an elliptical array on her bows. Before the battle of the Denmark Strait Prinz Eugen’s GHG tracked the Hood well over the horizon.

First steps toward the development of an efficient underwater detection system began in 1933, using a French Langevin set with piezo-electric transducers aboard the experimental vessel Grille and the Finnish submarine CV 707 as target ship during her builder’s trials in the eastern Baltic. However, the Germans were unaware of the poor conditions for sound propagation in this brackish, heavily layered body of water, and trials proved unsuccessful until shifted to the North Sea.

During the following years work concentrated on the development of an active acoustic location device, designated S-Gerät (Sondergerät), using magnetostrictive transducers. Following the manufactor of ten experimental sets in 1937, an additional nineteen were delivered to the navy during the summer of 1939. Of these, thirteen sets were installed on various vessels and the rest allocated to training establishments ashore. Antisubmarine fire-control systems were nonexistent at that time. At the start of the war, there existed almost no practical experience on their use, and the training of operators was in its infancy. Hydrophone or passive listening gear still formed the backbone of underwater location technique. By the summer of 1940 just ninety-one S-Gerät sets for installation on surface vessels were completed. Concentrating on the basic design features, production of a simplified version (Mob-S-Gerät) was started, of which almost fifteen hundred sets were delivered by the end of 1942 and installed on various classes of vessels.

 

 

At the service level, having undeveloped doctrine, insufficient sets for operations, let alone training, and having tremendous difficulty detecting and engaging submarines does not bode well for their major surface combatants masterfully using sonar in battle, but there are surprises there too. 

 

@theCarthaginian, the author does note the advanced set installed on Prinz Eugen, but mentions it tracking Hood. I don't see any reference to torpedos. The easiest thing to do would be to look for that  GHG (Gruppenhorchgerät) set:

Which "consisted of two rows with sixty Rochelle salt hydrophones at each side, arranged in an elliptical array on her bows."

And to find out more about the capabilities from there. A 120 hydrophone array is significant, but it still doesn't tell us much about the kind of information it provided. I would guess based on the example, and Germany's surface raider doctrine mentioned above, that it was intendant to track merchants (to attack) and warships (to evade). To use the radar example, that seems like an Early Warning Radar. I don't know enough about sonar to say if the implications for frequency, wavelength and resolution. 

Edited October 4, 2021 by DougToss

[madham82]

Food for thought, I don't think I heard of this before:

Torpedowarn (TAG)

Designed as an early warning system for incoming torpedoes, the TAG was installed on the Type XXI and intended for future generation U-boats. It was connected to a loudspeaker inside the pressure hull which would give audible warnings on an approaching torpedo. It functioned by listening in to certain pre-programmed sounds, which would trigger the alert status.

http://www.uboataces.com/hydrophones.shtml

Now if they could make an automated system in '44/'45, you bet an at least competent sonar operator could detect an incoming torpedo.  

[theCarthaginian]

31 minutes ago, DougToss said:

Just generally speaking, the U-Boat arm got the pick of the Kriegsmarine. By the time the major surface units were expected to do no more than be bombed at anchor, I’m not sure why they would prioritize sending the top of the sonarman class there. I’m sure I can poke around for something on how the Kriegsmarine was kitted out for ASW and how their acoustics were.

From O’Hara’s On Seas Contested: The Seven Great Navies of the Second World War:

Antisubmarine Doctrine

ASW Equipment

 

At the service level, having undeveloped doctrine, insufficient sets for operations, let alone training, and having tremendous difficulty detecting and engaging submarines does not bode well for their major surface combatants masterfully using sonar in battle, but there are surprises there too. 

 

@theCarthaginian, the author does note the advanced set installed on Prinz Eugen, but mentions it tracking Hood. I don't see any reference to torpedos. The easiest thing to do would be to look for that  GHG (Gruppenhorchgerät) set:

Which "consisted of two rows with sixty Rochelle salt hydrophones at each side, arranged in an elliptical array on her bows."

And to find out more about the capabilities from there. A 120 hydrophone array is significant, but it still doesn't tell us much about the kind of information it provided. I would guess based on the example, and Germany's surface raider doctrine mentioned above, that it was intendant to track merchants (to attack) and warships (to evade). To use the radar example, that seems like an Early Warning Radar. I don't know enough about sonar to say if the implications for frequency, wavelength and resolution. 

Yeah... the actual performance info on GHG transducers in general and the great socking linier array on P.E. in specific is quite limited. I've been looking between games of HOI4 since I got off work on Wednesday morning and have found precisely diddly-squat beyond what you mentioned.

All of which make the cited case look more like an outlying case rather than the mean performance of the set... more reason for me to doubt 🧐.

[theCarthaginian]

16 minutes ago, madham82 said:

Food for thought, I don't think I heard of this before:

Torpedowarn (TAG)

Designed as an early warning system for incoming torpedoes, the TAG was installed on the Type XXI and intended for future generation U-boats. It was connected to a loudspeaker inside the pressure hull which would give audible warnings on an approaching torpedo. It functioned by listening in to certain pre-programmed sounds, which would trigger the alert status.

http://www.uboataces.com/hydrophones.shtml

Now if they could make an automated system in '44/'45, you bet an at least competent sonar operator could detect an incoming torpedo.  

False assumption, again.

Machines do not 'hear.' They do not get distracted, they do not miss things; contrariwise, they cannot interpret info on the fly if the incoming data doesn't trip their preset parameters. They are, as my old high school math teacher loved to say 'high speed idiots.' They merely multiply the mistakes of others at incredible rates.

A particular pattern recognition in those early automated systems was not very reliable, was easily spoofed, and was very limited in range. Think about the difficulties that early homing torpedoes had... the system you mentioned would echo those problems... and came something on the order of a DECADE after P.E. was put into service. :-)

[arkhangelsk]

13 hours ago, theCarthaginian said:

1.) You are kidding, right?
The creme de la creme of sonar operators in the Kreigsmarine were put on a heavy cruiser? 🤣 I'm sorry, no... that's a MASSIVELY counterintuitive comment with neither grounding in rationality nor the ability to cite proof. Occam's Razor would lead one ot believe that the better sonarmen were on U-boats, simply by virtue of their ships' entire existence depending on how well that system is operated. Pulling a guy that can hear, differentiate, and triangulate targets at 40km from a sub to a surface ship is like taking the best door gunners in the Ia Drang valley out of their Hueys and making them Apollo Program Door Gunners. You lose any real utility that cannot be gained by other systems. We know this, because, no major Kreigsarine vessel was lost to surface-launched torpedoes in spite of several facing them. AGAIN, you are citing a single instance and applying the Mediocrity Principle in the face of convincing evidence across multiple nations that other circumstances point to this being an outlying case. Your argument is not based on logic, or it is rather based on bad logic.

You, sir, are not thinking it through. For your first point, again you are ignoring the sheer scarcity of heavy ships and the abundance of U-boats in the German navy. Suppose I have 10 ships, 990 U-boats and 1000 sonarmen to put on them.

If I put my best ten sonarmen on the ten ships, then the U-boats start with #11. The average of all the U-boat sonarmen will be (11+1000)/2=505.5. Meanwhile, I've significantly improved the survivability of my ten surface ships.

If I put my ten best sonarmen on the U-boat and deliberately give the ten worst sonarmen to the surface ship because the U-boat's "entire existence depending on how well that system is operated", the average of all the U-boat sonarmen will be (1+990)/2 = 495.5, a ten place improvement but still close to 500. Big deal. Meanwhile, I've significantly decreased the survivability of my ten surface ships.

Still want to put your best in the U-boat?

13 hours ago, theCarthaginian said:

2.) Again, you're making a false assumption. Lower frequencies carry farther in water than higher ones. This means that higher-frequencies - like what a torpedo gives off as opposed to, say, a churning Liberty ship propeller - attenuate FASTER and you won't hear them as far away. 🙂 Also, the Expansion engines that most merchant ships of the inter-war and WWII period used were orders of magnitude louder than a turbine-driven warship due to the fact that they caused far more vibration and impact forces that propagated through the structure and into the water. Turbines simply spin... the multiple expansion engines of a merchant ship and some escorts ware just like a car engine - a piston on a connecting rod that turned a crankshaft. If you own a car, fire it up and open the hood. Watch your engine sit and vibrate. Ever wonder why it isn't precisely hard-mounted to the frame, but instead has dampening mounts?
*ding, ding, ding*
We have a winner. 😄
So, your entire basis for the second part of your argument is utterly and irredeemably flawed.

It's me, not you. Here's why:

1) It's not the noisy one you are worried about not detecting by sound in time. It's the quiet one. You are worried about the one with turbines. Especially if it is an escort.

2) You are ignoring what is perhaps the biggest contributor to overall sound level - speed. 

Edited October 5, 2021 by arkhangelsk
Add 2nd portion, add picture

[arkhangelsk]

13 hours ago, theCarthaginian said:

PS - I find no records of Bismark or Scharnhorst having any sonar systems installed.
Could you point me toward your source for that?
If they did not, in fact, have them... well, you ARE dealing with a single instance - especially if those ships didn't exhibit exactly the same performance.

https://www.amazon.com/dp/B00SS5XGCS/ref=wl_mb_wl_huc_mrai_3_dp

https://www.amazon.com/Battleship-Bismarck-Design-Operational-History-ebook/dp/B07WWP9V8K/ref=sr_1_11?dchild=1&keywords=Prinz+Eugen&qid=1633405017&s=digital-text&sr=1-11

https://www.amazon.com/Heavy-Cruisers-Admiral-Hipper-Class-ebook/dp/B00SGC4YGA/ref=sr_1_14?dchild=1&keywords=Prinz+Eugen&qid=1633405017&s=digital-text&sr=1-14

That reminds me. I've been giving you free credit so far, but I still don't know the number of that stupid U-boat who said he can't hear jack, exactly what the source's name is, or exactly what it said...

[arkhangelsk]

14 hours ago, DougToss said:

From O’Hara’s On Seas Contested: The Seven Great Navies of the Second World War:

Doug, I applaud you for the effort in typing up so much text (I have NOT been able to find an Ebook version of On Seas Contested). However, none of what you quoted refutes the possibility of a good hearing system which is the debate at hand. All your text says is that they don't have very good active sonars or "fire control systems" or trained operators to use them. Your own text concedes that Hood was "tracked" well over the horizon, and I don't know how you can "track" something without bearing information.

Hydrophone or passive listening gear still formed the backbone of underwater location technique.

Might mean it is pretty good (I'm not saying good enough you can drop depth charges on it).

Quote

And to find out more about the capabilities from there. A 120 hydrophone array is significant, but it still doesn't tell us much about the kind of information it provided.

Here, have a picture:

I see it provides bearing information, approximate speed, approximate type.

Here are some for Bismarck:

 

The thing seems to work pretty well, the radar was knocked out and there's no point in trying tricky maneuvers if they can see the cruisers. Further, it's clear that the British cruisers were at the very edge of their own radar range.

Edited October 5, 2021 by arkhangelsk

[RedParadize]

@arkhangelsk @DougToss I am much more lazy than both of you, but I agree. Sorry to quote myself  but what you both said is more or less what  I meant when I said this:

On 9/28/2021 at 4:01 PM, RedParadize said:

By the times of ww2 torpedo detection was indeed good enough to detect incoming torpedo. One thing that isnt taken into consideration is that there was basically only one sonar, with one guy pointing it in a specific direction. With the sonar you get the incoming direction of the noise pretty accurately, but for the bearing and distance you can only rely on guesswork. The talent of the sonar operator could vary greatly and in a intense battle, where there is multiple boat and multiple incoming torpedo, things get much more complicated. Reality is that sonar equipped boat were indeed getting torpedoed in ww2.

On 10/1/2021 at 5:39 PM, RedParadize said:

I think that a great deal can be explained trough the context in which sonar was used. Do not forget that they were human operated, single direction device and subject to the environment in which they were operated. It isn't surprising that both terrible and great performance were recorded

 

[theCarthaginian]

Ok... Nice charts. You don't give any context though. You can plunk down charts all day long without context and it means little. Cavitation, for instance, isn't an absolute limit. It's a function of multiple things: RPM, pressure, blade geometry, etc. Two otherwise identical plants can have different geometry screws and cavitate at different points.
Speed being a function of noise is correct, but it is not THE BIGGEST FACTOR, as a turbine powered ship is MUCH QUIETER at a given speed than a ship powered by expansion engines at an equal speed. Indeed, even on a modern submarine, the lower frequencys are heard first and farthest away. The higher-frequency noises, again, do not propagate as for for a given energy. It's why you hear whale songs documented as being heard literally oceans away... frequency, frequency, frequency.

 

You apparently misunderstand about me asking for Bismark and sonar info. I genuinely did not know (or indeed, care) if she mounted one. We see all the good it actually did her, too... so your whole 'statistics show' argument fails the test of logic. Having a good or bad sonar operator didn't save Bismark, Tirpitz, or any other German 'major surface combatant.' Putting 'the best' on them sinply takes those men and removes them to vessels that spent majority of their operational lifespans accomplishing very little effect. German surface raiders had a single major hurrah, and the Twins did that relatively early on - 08JUN40 to be precise. By the end of 1941, though, the German surface raider was a useless concept and the German surface fleet had largely taken up hiding in port as an occupation and sorties became a mere hobby.

The U-boats, by contrast, made meaningful contributions right up till the end of the war. Indeed, U-2511 could have sank a British cruiser (per her logbook, since you like to cite those as inviolate) on the day of the surrender.

 

If you want me to dig up exactly which boats heard what when you'll have to let me dig up copies of books I haven't read in a fair bit. my U-boat fanboy period ended quite early and most of the books on German naval hardware got shelved a couple of decades ago in favor of books on PACT hardware out of relevant professional interest. I'll give a dive for them though, to be fair.

[DougToss]

I have to applaud @arkhangelsk for putting the work in. I appreciated reading what you put together there.

 

Me, when @arkhangelsk writes pages of notes and research:

https://m.youtube.com/watch?v=2fWr6CBARMw

Edited October 5, 2021 by DougToss

[HistoricalAccuracyMan]

On 9/24/2021 at 5:32 PM, theCarthaginian said:

I'm a bit confused as to how an OPFOR destroyer - which is making smoke - can notice that I am - while also making smoke - am launching torpedoes several kilometers away and immediately react by going hard over to let a spread of five torpedoes whizz by totally ineffectually. It seems that the AI is as acutely aware of our actions during combat as it is in how our ships are designed in order to counter our tactics.

Exactly what penalties in spotting is the AI suffering due to two smokes and at what range are the torpedoes of each type visible both in and out of smoke?

As much as I have enjoyed learning about sonar/hydrophone systems and how they've advanced, how they work, etc...I think the central idea/question of this thread has been kinda lost a little bit, but I'll try and answer everything in the above original post/question to the best of my ability.

Yes, it seems ridiculous that from ranges of 10 km or further an enemy ship can almost instantaneously detect your torpedoes and evade them. Why is that? I honestly don't know. But when you look at all the changes the AI has gone through with patches and hotfixes, the AI has gone through "weird" or "troublesome" stages: nearly everything from regularly making insane/wacky designs, prioritizing speed above all else, being able to dodge torpedoes effortlessly and a handful of other "flaws." (I'm not saying this as an excuse, I'm just saying that it will eventually be fixed or ironed out in due time) Yes it's frustrating, but nobody knows exactly why.

When it comes to smoke screens and the associated penalties, the biggest ones are the "shooting through smoke" and the "target inside smoke" obviously. As far as torpedo spotting goes when in smoke, I would assume that only the visual detection of torpedoes would be effected as a sonar/hydrophone doesn't care that there is smoke obstructing line of sight, and therefore you would be relying only on your sonar/hydrophones to detect the incoming torpedoes (which makes sense, as a smokescreen's purpose is to obstruct or block line of sight)...IF there is a "debuff" to visual torpedo spotting inside a smoke screen in the first place. I don't know whether or not a smoke screen negatively effects visual detection of torpedoes as in all the custom battles I've set up, the tech levels of each nation are either so low that torpedoes don't have the range to hit a smoked up target or the sonar/hydrophone that I or the enemy have mounted detect the torpedoes at range and the intended target can maneuver to avoid. I guess I could set up a few tests to see for my self, if I really wanted to. As far as your "penalties suffered by the AI due to two smokes" query is concerned, there is the "shooting through smoke" and "target inside smoke" penalties...but I, again, have zero clue about torpedo spotting inside smoke and what, if any, penalties are associated with it.

Now, torpedo spotting while outside of a smokescreen is directly influenced by any sonar/hydrophone upgrades you have mounted and the "torpedo spotting" stats of the towers you mount on your ship (once weather and time of day effects get added, I'd assume that rough seas, storms and nighttime would make torpedo spotting harder...visually speaking anyways). With the introduction of the new crew mechanics, I would also assume that how experienced your crew is might also slightly effect how far out you can spot torpedoes.

As far as how far away each torpedo type can be detected at, I really don't know either. Each torpedo type (standard, fast, electric and oxygen) all just have a different stealth/detectability percentage, but not much else, as I'm sure you already know. I personally think it would be helpful if each torpedo type had a base detection range/stat (as in range from intended target) and then your ship tower's torpedo spotting stats and any hydro/sonar upgrades you had increase the detection range of that torpedo by a certain percent of the base detection range/stat of said torpedo. (Idk if that sounds too much like WoWs style torpedo spotting, but it would be better than just seeing "these electric torpedoes have a -85% detection bonus")

Most of this is just speculation or trying to make an educated guess/assumption based on what we know and what would make sense. In the end, I can see why the devs made sonar/hydrophones the way they did: if they go too realistic with it, then yes--the sonar/hydrophones on your ship would be useless depending on speed, vibration of your ship, weather and sea conditions, etc and there would be little/no reason to use it unless you were building convoy escort ships so they could listen for submarines or incoming torpedoes (but subs aren't even in the game, so....). But on the other hand, they can't go too "cut and dry" or "either/or" if you will: with technology level being a big part of ship design and what tech you have available, it makes sense that as time marches on...you get access to better, but heavier and more expensive, systems to use as opposed to just "option 2 is more effective/high tech while option 1 is cheaper and more lightweight."

Ultimately, as I've said before, this is a game that is historically based and not historically accurate (excluding hull, tower and gun models). Will there be stuff that doesn't make sense in a real life context or that seem down right absurd? Absolutely. But sometimes those things make sense from a gameplay standpoint like this sonar/hydrophones issue. If they went ahead and made the sonar/hydro super realistic thus rendering those systems all but useless in high speed, open ocean, ship-to-ship combat (as is the main focus of this game)...why would they have added sonar/hydro in the first place?

TL;DR: In response to the original question...I don't know, I wish I knew and your guess/inferences are as good as anyone's. We can sit here and speculate/guess/debate using logic, research notes/sources, prior and firsthand knowledge all we want for as long as we want, but until somebody runs some tests or we get a full explanation from somebody who does know exactly how all this works in game and why it works that way...we just have to live with it.

Edited October 6, 2021 by HistoricalAccuracyMan

[DougToss]

I've genuinely forgotten, but how do other sims detect torpedoes? I know RTW2, Jutland Pro, and The War at Sea all have AI that will evade and keep formation, to the best of their ability, and I know torpedoes are not always visible, and often come as a surprise too late to evade, but I can't recall how exactly they are spotted. On the other side of the equation, in Silent Hunter 4/5, Wolf Pack and U-Boat, enemy detection of torpedoes is also variable. 

Does anyone know?